Telephone system



Feb. 25, 1930. w. H. MATTI-"Es 1,748,239

TELEPHONE SYSTEM A Filed Nov. 19, 1928 2 Sheets-Sheet l N Nl l@ HY. WW

A TTUHNEY Feb. 25, 1930. w. H. MATTHIES 1,748,239

TELEPHONE SYSTEM Filed Nov. 19, 1928 2 Sheets-Sheet 2 /NVE/v 70H W MA 7TH/Es Patented Feb. 25, 1930 UNITED STTES PATET OFFICE WILLIAM H. MATTHES, OF HCKENSACK, NEW' JERSEY, ASSIGNOR TO BELL TELE- PHONE LABORATORIES, INCORPORATED, OF NEVT YGRK, N, Y., A CORPORATION OF TELEPHONE SYSTEM Application filed November 19, 1828. Serial No. 320,302.

r@This invention relates to operating and control circuits and particularly to impulse circuits for selective switches.

The objects of the invention are to increase the effective range over which impulses may be sent, to simplify the equipment used in impulse receiving circuits and to render these circuits more reliable during change-over operations.

Heretotore, plans have been devised for niaking a relay slow to release its armatures during interruptions caused by the sending ot' impulses for setting selective switches and similar devices. In some cases the relay is made slow by means ot a special design of its magnetic circuit, while in other instances mechanical expedients are involved.

According to the present invention, these expedients are obviated and an ordinary relay is employed. This relay is prevented from releasing during the transmission of impulses by so arranging the Circuits that during the intervals its original operating circuit is open the relay is sustained by a d1- reet shunt path about its winding and by parallel paths through its winding and locling contacts Furthermore, for each impulse delivered lo the switch operating magnet, an induced current, caused by breakiiuf the magnet circuit, is directed througl'l the relay, tesuling to sustain its energization.

feature of the invention is a circuit in wh Ich one et the parallel paths tor supplying euri-eat to :he relay also acts to shunt a portion et the inductive surge coming trom the inap-,mitq thus protecting the contacts on the impulse relay without the use ot a condenser.

According to another feature the relay is guarde( against accidental release by one ot' said parallel current supply paths while the other path is momentarily opened to eltect a changeover operation.

The drawing discloses a selector circuit and a connector circuit, both ot which einl'iody the features et' tA s invention. In Figure 1 a callingl subscribers station A is diagrammatically shown connected by the line 100 and by a line finder or some other eiplivalent means to the line leads ot selector S. Yln Figure 2 a connector circuit C is shown di- ;igrannuatically connected over line 200 t0 a called subscribers station B. Figures 1 and 2 together' may be used to illustrate the establishment ot a call from station A to station B, the operation of the selector S being controlled by the dialing of the first digit ot the called stationz; number and the operation oil the connector' C being controlled by the dialing` ot' the last two digits ofthe called stations number.

With the station A and selector S connected as illustrated, relay 101 of selector t operated by an obvious circuit which ncludes the line 100, back contacts of :clay 10T, both windings of relay 101, normally closed contacts of the 11th rotary s Y springs, and the secondary Winding oi the dial tone induction coil. 111 operating, relay 101 closes a circuit from battery through res ance 100, in parallel with the windings of vertical stepping magnet 103 and relay 101- connected in series, through lead 112` winding of relay 102, lead 111, and through the front contact and armature of relay 101, to ground. Relay 102 is operated by this circuit but vertical magnet 103 and relay 101 are not operated on account ot the reshtanee ot' relay 102 and on account ot their windings being shunted by resistance 109. in operati relay 102 connects ground to lead 110 so as to hold the connection between lie station A and selector S. ln operating, relay 102 also cenneets ground through its louer inner front contact and armature to lead 111 so that the circuit through the windings oi relay 102, resistance 100, magnet 103 a id relay 101 will not be opened by the release r relay 101 as hlaeinafter described.

Yfhen the calling subscriber dials the iirst digit ot the called stations number, relay 101 releases and reoperates each time the line circuit is opened and closed at the contacts of the dial. lilach release ot relay 101 connects ground through its back Contact, and through the inner upper armature and front cuntact of relay 102, to leadv 112 thereby short-circuiting the winding of relay 102 and causing the operation ot' vertical stepping magnet 103 and relay 104. The reoperation of relay 101 after each release removes the short-circuit around the winding ot" relay 10Q, causing the release ot the vertical magnet. Relay 101 is a slow-to-release relay and remains in its operated position until all ot the dial pulses correspoinling to the {irst digit of the called number have been received. Each operation oit the vertical stepping magnet steps the brushes of the selector up one level. Vtelay 102 has no slow-torelease characteristic but the circuit arrangement is such that during the time that the armature oit' relay 101 1s traveling between its 'liront and back contacts, either on release or reoperation. the energization ot relay 102 maintained by the ground connected through its inner lower front contact and armature to lead 111; when the armature ot relay 101 is touching its back contact, dur'ng dialing, the de-energization ot' relay 102 is retarded by a self-induced current through its shortcircuited winding; and when this short circuit is removed by the reoperation relay 101, the energization ol' relay 102 is quickly restored by the circuit which includes the lower inner armature and front contact of relay 102 and includes the windings oit inagnet 103 and relay 101 in parallel with resistance 109, the restoration being aided by an inductive surge from the winding of the vcrtical stepping magnet. This circuit arrangement, whereby the surge from the vertical magnet is absorbed by the winding of relay 102 and by the resistance 10S), makes it unnecessary to furnish other protection Vfor the contacts of relay 101.

As soon as the shaft and multiple izfzaisnes4 ot the selector are stepped up to the lirst` level the vert' lal off normal springs l'. are actuated and a circuit tor operating lay 105 is closed. This circuit may be trac from battery through the winding ot rei 105, lower contacts ot the V. t). N. sprii armature and front contact` ot relay 10 l. leid 110, and through the outer upper armature and Jfront contact ot relay 10'2, to ground. Since relay 104 is slow to rel ase, this eircuit is closed in all cases including that in which only one dial pulse is created by the dialing of the first digit of the called inunber. In operating, relay 105 closes a locking circuit from battery through its winding. lower contacts of the V. O. N. spring-1. back contact and armature of the rotary steppin magnet 106, and through the lett-hand trout contact and arn'iature ot relay 105, to ground. lhen relay 101 reoperatc-s. attcr the last pulse of the series which are created by the dialing of the tirst digit. both vertical inagnet 103 and relay 105irelease. The multiple brushes 113, 114 and 115 are now in position opposite the level ot terminals which corresponds to the lirst digit dialed.

When relay 101 releases, a circuit is closed from battery through the winding of the rotary stepping magnet 10G, through the righthand armature and front contact ot relay 105. normally cloi-cd contacts of relay 104, lead 110, and through the outer upper armature and trout contact ot relay 102, to ground. The olary magnet 100 operates in this circuit advancing the multiple brushes into contact with the tirst set oi terminals in the selected level. ln operating, the rotary magnet 100 opens the circuit through the windingot relay 105, thus causing the relra-e of relay 105. In releasing, relay 105 opens the circuit through the winding of the rotary magnet 100, thereby releasing the rotary magnet. A circuit may now be traced trom battery through the winding of relay 105. lower contacts ot the Y. O. N. springs, bach contact of the rotary magnet 100, winding et relay 1( 7. and through lower contacts ot the 11th rotary step springs, to the ground on lead 110. It the tirst set ot terminals in the selected level is idle relay 107 is operated in this circuit, but relay 105 is marginal and does not operate in se with the winding` ot relay 107. Vlt the lirst set of terminals is busy relay 105 reoperates, but relay 107 does not operate since its Winding is shortcircuited by a busy ground on the test terminal 118. The circuit tor reoperating relay 105 may be. traced from battery through its winding, through the lower contacts on the V. N. springs, back contact of the rotary magnet 100. back contact and inner lower armature ot relay 107, and through the test brush 115, to ground on the test terminal 118 of the busy trunk. The reoperation ot' relay 105 closes the circuit through the winding of the rotary stepping magnet 106, thereby advancing brushes 11?, 111, and 115 to the second set of terminals in the selected level. 'lhc alternate operation and release of relay 105 and magnet 100 continues until the test brush 115 makes contactr with the test terminal ot' an idle set, at which time the winding of relay 107 is no longer short-circuited and relay 107 operates. The operation of relay 107 opens the circuit through the windings ot relay 101, connects the calling line 100 through brushes 113 and 114 to terminals 11G and 117 of the selected idle trunk, opens the circuit from battery through the windings ot vertical magnet 103 and relay 104. and connects a temporary make-busy ground to test terminal 118 of the selected trunk. rthis malte-busy circuit may be traced from ground through the trent contact and outer upper armature ot relay 102, lead 110, front contact and inner lower armature of relay 107, and through test brush 115 to test terminal 118. Relay 102 is held operated, temiliorarily, by the circuit troni battery through resistance 109 to ground through its inner lower armature and i'ront contact; and as soon relay 101 releases, the winding of relay 102 is shorti-circuited by the ground on the armature and through the back Contact of relay 101. The consequent release of relay 102 is slow so that a permanent makebusy ground is connected to test terminal 118, by the selected trunk circuit, before relay 102 disconnects the temporary make-busy ground from this terminal. It should be noted that relay 102 is held operated at the time of the release of relay 101 without the use of continuity contacts on relay 101, this desirable result being due to the use of resistance 109 and the temporary holding circuit thereby provided. After relay 102 has released, relay 107 is held operated by the ground on terminal 118; this circuit may be traced from battery through the winding of relay 105, lower contacts of the V. C. N. springs, back contact of rotary magnet 106, winding of relay 107, lower contacts of the 11th rotary step springs, front contact and inner lower armature of relay 107, and through brush 115, to the make-busy and holding ground on terminal 118.

The selected trunk may terminate in a connector such as C shown in Fig. 2 or may terminate in another selector. lf additional selectors are used in completing the connection between the calling line 100 and the connector C their operation is controlled by the dialing of additional digits of the called number. In all cases the dialing otl the last two digits of the called number controls the operation of the connector C.

In the following description it is assumed that the selected trunk connects directly to the connector C shown in Fig. 2. Relay 201 is operated by a circuit which includes both windings of relay 201, outer back contacts of relay 207, terminals 11G and 117 and brushes 113 and 114 of selector S, outer front contacts of relay 107, and the line 100. In operating, relay 201 closes a circuit from battery through resistance 209, in parallel with battery through the windings of vertical stepping magnet 203 and relay 204 in series,

' through lead 212, winding of relay 202, lead 211, and through the front contact and armature of relay 201, to ground. Relay 202 is operated by this circuit but vertical magnet 203 and relay 204 are not operated on account of the resistance of relay 202 and on account of their windings being shunted by resistance 209. In operating, relay 202 connects ground through its outer lower armature and front contact to lead 210 so as to hold the connection between the preceding selector and the connector C, and connects a locking ground through its inner lower armature and front contact to lead 211.

lVhen the calling subscriber dials the next I" to the last digit of the called stations number relay 201 releases and reoperates each time the line is opened and closed at the contacts of the dial. Each release of relay 201 connects ground through its back contact, and

through the inner upper armature and front contact of relay 202, to lead 212, thereby short-circuiting the winding of relay 202 and causing the operation of vertical stepping magnet 203 and relay 204. The reoperation of relay 201, after each release, removes the short-circuit around the winding of relay 202, thus causing the release of the vertical magnet. Relay 204 is a slow-to-release relay and remains in its operated position until all of the dial pulses corresponding to the next to the last digit of the called number have been received. Each operation of the vertical stepping magnet steps the brushes of the selector ap one level. Relay 202 has no slow-to-release characteristic but the circuit arrangement is such that during the time that the armature of relay 201 is traveling between its front and back contacts, either on release or reoperation, the energization of relay 202 is maintained by the ground connected through its inner lower front contact and armature to lead 211; when the armature of relay 201 is touching its back contact, (hiring dialing, the de-energization of relay 202 is retarded by a self-induced current through its short-circuited winding; and when this short-circuit is removed by the reoperation of relay 201, the energization of relay 202 is quickly restored by the circuit which includes the windings of magnet 203 and relay 204. in parallel with resistance 209, the restoration being aided by an inductive surge from the winding of the vertical stepping magnet. This circuit arrangement, whereby the surge from the vertical magnet is absorbed by the winding of relay 202 and by resistance 209 makes it unnecessary to furnish other protection for the contacts of relay 202.

As soon as the shaft and multiple brushes are stepped up to the first level the vertical off-normal springs V. O. N. are actuated and the circuit for reoperating vertical magnet 203. and for preventing the release of relay 204 (until all of the pulses corresponding to the digit dialed have been received), is now traced through the front contact and armature of relay 204 and upper normally open contacts of the V. C. N. springs, instead of through the normally closed contacts of the V. C. N. springs. W'hen relay 201 reoperates at the end of the series of dial pulses Which are created by the dialing of the neXt to the last digit of thc called stations number, both vertical magnet 203 and relay 204 release. rthe release of relay 204 closes a circuit from battery through the winding of rotary stepping magnet 206 and back contact of relay 221. in parallel with battery through the winding of relay 205, through the right-hand armature and back contact of relay 220, back contact of relay 204, upper normally open contacts of the V. O. NA springs, lead 212, winding of relay 202, and through the front contact and armature of relay 201, to ground. Relay 202 is held operated by this circuit but rotary magnet 206 and relay 205 do not 0perate on account of the resistance of relay 202 and on account of their windings being shunted by resistance 209. The multiple brushes 213, 214 and 215 are now in position opposite the level of terminals which corresponds to the digit dialed.

lt should be noted that relay 201 is equipped with a set ot transfer springs rather than with a set ot continuity springs and that the use ot the transfer springs is desirable since they are more easily maintained in adjustment. ln the past it has been necessary to use continuity springs in order to prevent the release of the relay corresponding to relay 202 during the change-over from the delivery oit impulses to the vertical magnet to the delivery ot impulses to the rotary magnet. Although transfer springs are used in this circuit, the release of relay 202, during this change-over, is prevented by the holding circuit which is traced from battery through resistance 200, lead 212, winding ot relay 202.y and through the inner lower armature and front Contact ot relay 202, to ground.

llvhen the calling subscriber dials the last digit of the called stations number, which we will assume to be 3. relay 201 releases and reperates as many times as there are units in that digit. The first release of relay 201 connects ground through its armature and back contact and through the inner Lipper armature and front contact of relay 202, to lead 212, thereby short-circuiting the winding of relay 202 and causing the operation of relay 205 and rotary magnet 206. The operation et the rotary stepping magnet 20G advances the brushes 213, 211, and 215 into contact with the tirst set of tern'iinals in the selected level. The right-hand contacts of relay 220 are .shunted by the lett-hand contacts ot relay 205 when relay 205 operates, so that the circuit tor energizing the windings ot relay 205 and rotary magnet 206 is no longer under the control ot relay 220.

lith the multiple brushes in contact with the irst set of terminals in the selected level, a circuit is closed from battery through the winding ot relay 220, inner lower armature and back contact of relay 221, front contact and right-hand armature ot relay 205. and through brush 215 to the test terminal 218 of the first set. If this set of terminals is busy, test terminal 218 is grounded and relay 220 may operate, but, since the units digitot the called number is 3, the operation or non-operation of relay 220 prior to the multiple brushes being in contact with the third set of terminals is immaterial. Vhen relay 201 reoperates, after its tirst release, rotary magnet 200 releases but since relay 205 is a slow-to-release relay it remains operated until all of the pulses corresponding to the last digit have been received. Relay 202 remains in its operated position, during the dialing ot the last digit, for the same reasons as when the next to the last digit of the called number was being dialed; the only difference is that the winding of the rotary magnet 20G, in parallel with the winding of relay 205, is included in the circuit in place ot the winding ot the vertical magnet 203, in series with the winding of relay 204, so that the winding ot relay 202 and the resistance 20S) absorb the surge from the rotary stepping magnet 206 each time relay 201 reoperates.

Then the last pulse has been received and test brush 215 is in contact with the test terminal of the called line and before relay 205 releases` relay 220 operates if the called line is busy. This circuit may be traced trom battery through the winding of relay 220 in ner lower armature and back contact of relay 221, right-hand armature and tront contact ot relay 205, and through test brush 215. to ground on the test terminal 218. The operation ot' relay 220 connects busy tone to the ring lead of the incoming trunk. The release of relay 205 then closes a locking circuit tor relay 220 under control of relay 202. It the called line is idle relay 220 does not operate and when relay 205 releases a circuit is closed from battery through the winding ot the cut ott relay (not shown) of the called line, through test terminal 21S, test brush 215. right-hand armature and back contact of relay 205, lower winding of relay 221, inner left-hand armature and back contact of relay 220, and through the outer lower armature and front Contact ot relay 202, to ground lelay 221 operates in this circuit and closes a locking circuit through its upper windingr to ground at the upper outer armature and front contact of relay 202. In operating re lay 221 also closes the ringing circuit from the ringing current source 222, through the second upper armature and front contact ot relay 221, lower winding of relay 210, outer lower armature and back contact of relay 212). outer lower armature and front contacV ot relay 221, multiple brush 214 and line terminal 217, loop of the called line 200, line terminal 216 and multiple brush 213, outer upper armature and Vfront contact of relay 221. and through the outer upper armatur:` and back contact of relay 219, to ground. Audible ringing tone is transmitted through condenser over the ring side ot the incoming trunk to the calling subscriber.

lVhen the called subscriber answers, relay 21S) operates and it locks through its upper winding to ground at relay 202. In operating relay 219 opens the ringing circuit and connects battery through the upper winding ot relay 207 and ground through the lower winding of relay 207, through Jfront contacts on relays 219 and 221, and through multiple brushes 213 and 214, to the called line. Relav 207 operates in this circuit thereby reversing the battery and ground through the windings of relay 201, with respect to the tip and ring leads of the incoming trunk, to indicate that the called subscriber has answered. The operation of relay 207 also supplies a holding ground at its inner lovver armature and front contact Vfor relays 219 and 221 'which is independent of relay7 202, The incoming trunk is connected through condensers 222 and 223 and through the 'liront contacts of relays 219 and 221 to the called line for talking.

lVhen the connection is released by the calling subscriber the circuit tor relay 201 is opened. The consequent release ot relay 201 causes the release ot relay ln releasing, relay 202 removes the holdii. on"oun d from lead 210 so that relay 10T ol elector S releases. A busy potential is 'ntained 0n lead 210 by the ground on the ivi. to the lowest armature of relay thro'i i the right-hand armature and hack contact of relay 205, lower Winding of relay 1.1, and inner left-hand armature and buck contact of relay 220, to prevent the seizure oi this connector on another call until the subscriber has replaced the receiver at the called station. Vw' hen the called subscriber hangs up the receiver, relay '.7 releases thereby causing the release of relays 219 and 221. The release of relay 221 closes a circuit .trom battery through the Winding ot the release magnet 208,1ower contacts of the V. (l. N. springs, back contact of relay 221 and back contacts of relays 202 and 201. to ground. The operation of the magnet 208 in this circuit returns the connector shaft and multiple brushes to normal. lVith the shaft in its normal position the circuit through the release magnet 208 is opened by the restoration of the V. O. N. contacts to normal.

lVhen the make-busy and holding ground is disconnected from terminal 118 in the bank of selector S (by the release of relay 202 in the connector C), relay 107 ot Ylector S closes a circuit from battery through the Winding oi release magnet 108. upper contacts of the V. O. N. springs, back contact of relay 107, back contact oic relay 102, and through the back contact ot relay 101, to ground. The release magnet 100 operates in this circuit to cause the return ot' the multiple brushes to normal. lVhen the brushes reach their normal position, the V. (V). N. springs are shifted to normal thus opening the circuit through the Winding of the release magnet 108.

While the features ot this invention have been shown embodied in a particular selector and a particular connector it is understood that the invention is not limited to selector and connector switches or to switches of the step-by-step type, but is applicable to all systems in Which numerically directive impulses are received by means provided for this purpose.

What is claimed is:

1. In combination, an impulse receiving relay, a magnet for operation in response to impulses received by said impulse relay, a control relay cooperating with said impulse relay to deliver impulses to said magnet, a non-inductive resistance, and circuits including contacts of said impulse relay for operating said control relay, one of said operating circuits including the Winding of said magnet, the other ot said operating circuits including said non-inductive resistance.

2. In combination, an impulse receiving relay, a magnet for operation in response to impulses received by said impulse relay, a control relay cooperating With said impulse relay to deliver impulses to said magnet, a non-inductive resistance, circuits including contacts of said impulse relay for operating said control relay, one of said operating circuits including the Winding of said magnet, another ot said operating circuits including said non-inductive resistance, and a circuit for holding said control relay While impulses are being received.

3. In combination, an impulse receiving relay, a magnet for operation in response to impulses received by said impulse relay, a control relay cooperating with said impulse relay to deliver impulses to said magnet, a non-inductive resistance, a circuit including contacts of said impulse relay for operating said control relay, and circuits for holding said control relay While impulses are being received, one of said holding circuits including the Winding ot said magnet, another of said holding circuits including said non-inductive resistance.

l. In combination, an impulse receiving re lay, a magnet for operation in response to impulses received by said impulse relay, a control relay cooperating with said impulse relay to deliver impulses to said magnet, a non-inductive resistance, a circuit including contacts of said impulse relay for operating said control relay, and circuits for holding said control relay While impulses are being received, one of said holding circuits including the Winding ot said magnet, another of said holding circuits including said non-inductive resistance, and a third one of said holding circuits including contacts of said impulse relay.

5. ln combination, an impulse receiving relay, a magnet for operation in response to impulses received by said impulse relay, a control relay cooperating with said impulse relay to deliycr impulses to said magnet, a non-inductive resistance, circuits including contacts ot said impulse relay for operating said control relay, one of said operating circuits including the Winding of said magnet, the other of said operating circuits including said non-inductive resistance, and circuits tor holding said control relay operated while impulses are being received, one of said holding circuits including the Winding ot said magnet, the other ol said holding circuits including said non-inductive resistance.

6. In combination, an impulse receiving relay, a magnet for operation in response to impulses received by said impulse relay, a control relay cooperating with said impulse relay to deliver impulses to said magnet, a non-inductive resistance, circuits including contacts of said impulse relay for operating said control relay, one of said operating` circuits including the Winding of said magnet, the other of said operating circuits including said non-inductive resistance,and circuits for holding said control relay operated While impulses are being received, one ot said holding circuits including the windingl ot said magnet, another of said holding circuits including` said non-inductive resistance, and a third one of said holding circuits including contacts ot said impulse relay.

7. In combination, an impulse receiving relay, a magnet for operation in response to impulses received hy said impulse relay, a control relay cooperating with said iinpulse relay to deliver impulses to said magnet, a non-inductive resistance, a circuit including contacts ot said impulse relay for operating said control relay, a circuit for holding said control relay While impulses are heilig received. and a circuit including said resistance for absorbing the inductive surge from said magnet each time said impulse relay reoperates.

8. In combination, an impulse receiving relay, a magnet for operation in response to impulses received hy said impulse relay, a control relay cooperating with said im-v pulse relay to deliver impulses to said magnet, a circuit including an armature and a front contact of said impulse relay Jfor operating said control relay, and a circuit including said armature and a hack contact of said impulse relay and including a contact of said control relay for holding said control relay While impulses are being received.

9. In combination, an impulse receiving relay, a magnet tor operation in response to impulses received by said impulse relay, a control relay cooperating with said impulse relay to deliver impulses to said magnet, a circuit including an armature and a front contact ot' said impulse relay for operating said control. relay, and circuits for holding said control relay while impulses are being received, one oi said holding circuits ineluding said armature and a hack contact ot said impulse relay and including a contact ot said control relay, the other of said holding circuits being independent of said impulse relay.

l0. In combination, an impulse receiving relay, a magnet for operation in, response to impulses received hy said impulse relay, a control relay cooperating with said impulse relay to deliver impulses to said magnet, an auxiliary relay, a circuit including the Winding ot said auxiliary relay for operating said magnet, a circuit tor operating said control relay, and circuits for holding said control relay vvhile pulses are being received, one of said holding circuits including the windings of said magnet and said auxiliary relay, another ot said holding circuits excluding said magnet and excluding the contacts ot' said impulse relay.

ll. In combination, an impulse receiving relay, a magnet ior operation in response to a tiret train of impulses received by said impulse relay, a second magnet tor operation in response to a second train of impulses received hy said impulse relay, a control relay cooperating vvith said impulse relay to deliver said irst and second trains of impulses to said tirst and second magnets respectively, an operating circuit `for the control relay including a contact of the impulse relay, and circuits independent of the contacts ot the impulse relay and independent of said magnets for holding the control relay operated.

12. In combination, an impulse receiving relay, a magnet for operation in response to a first train of impulses received hy said impulse relay, a second magnet for operation in response to a second train of impulses received hy said impulse relay, a control relay cooperating With said impulse relay to deliver' said first and second trains ot impulses to said first and second magnets respectively, an operating circuit for the control relay including a contact of the impulse relay. and circuits independent of the contacts ot the impulse relay and independent of said magnets for holding the control relay operated each time said impulse relay releases during the reception ot impulses and for holding the control relay operated during the change-over from the delivering of impulses of said tirst train to said first magnet to the delivering of impulses ot said second train to .said second magnet.

13. In combination, an impulse receiving relay, a magnet tor operation in response to a llrst train of impulses received by said impulse relay, a second magnet Vtor operation in response to a second train ot' impulses rcceived by said impulse relay, a control relay` cooperating with said impulse relay to deliver said first and second trains ot impulses to said lirst and second n'iagnets respective y. an operating circuit for the control relay in-r cluding a contact of the impulse relay, circuits independent of the contacts of the impulse relay and independent of said magnets for holding the control relay operated each time said impulse relay releases during the reception of impulses and for holding the control relay operated during the changeover from tlie delivering in'ipulses of d first train to said lirst marr et to the deliver'- ing: of impulses of said second train to said second magnet, a circuit 'mr qufclrly restoring the energization of the control relay to ils former full value and l'er absorbing; tlle inductive surge from tlie winding' el said first magnet Wlien said impulse relay reopen'- ates after each impulse oi' s.id tirs-t train, said 'estoringf circuit including: sai-:l first magnet and said control relay. and a circuit for quickly restoring' llie energriZation of the control relay to its former 'ull value and 'l'or absorbing tlie inductive surfe from tlie Winding' of said secon l magnet Wlien said impulse relay reoperates after eaeli impulse of said second train, 'lie second of said restoring' circuits including said second magnet and said control relay.

il. ln combination, an impulse receiving' relay, a magnet for operation in respfmf-fey to impulses received by said impulse relay, a control relay cooperating with said iinn pulse relay to deliver impulses to said magnet, a non-inductive resistance connected to the Winding of said control relay, an operating circuit for the control relay including a Contact of tlie impulse relay, a holding circuit for said control relay closed While tlie armature of said impulse relay is moving between its normal and its operated position, a circuit for preventing' the release ot tlie said control relay vi'liile the armature of said impulse relay is in its normal posilion during the reception et impulses, and a eirc'ait includingl said noninf,luctive resistance for restoring tbe energization ot said control relay when the armature of said impulse relay resumes its operated position during *die reception of impulses.

l5. In combination, an impulse receivingr relay, a magnet for operation in response to impulses received by said impulse relay, a control relay cooperating with said ingr-.ilse relay to deliver impulses to said magnet, a non-inductive resistance permanentl,y connected to the windimry of said control relay, an operating circuit for tlie control. relay including a Vcontact oi tlie impulse relay. a holding' circuit for said control relay closed Wliile tlie armature o'l` said impulse relay is 1n ving between its normal and its operated position, said holding circuit includingr the windings of said magnet and said control relay, a circuit for preventing the release of said control relay While the armature of said impulse relay is in its normal position during the reception of impulsos, said last mentioned circuit being independent ot said magnet, and a circuit including said noninductive resistance for quickly restoring the energization of said control relay when the armature of said impulse relay resumes its operated position during' the reception of impulses.

lo. In combination, an impulse receiving relay, a magnet for operation in response te impulses received b1, said impulse relay, a control relay cooperating with said impulse relay to deliyer impulses to said magnet, a non-inductive resistance connected to the 'inding' o said control relay, an operating circuit for tlie control relay including a contact ot the impulse relay, a holding circuit for said control relay closed ivliile the armature or said impulse relay is moving; between irs normal and its operated position, a ciruit tor preventing tlie release of the said relay Wliile tlie armature of said iin- Muse relay is in its normal position during 'the reception of impulses, and a circuit including said non-inductive resistance for restoring the energization of said control relay and for absorbing' tlie inductive surge from llie Windingy of said magnet when the armature oi said impulse relay resumes its operated position during' the reception of impulses.

ln witness whereof, l hereunto subscribe my naine this 8th dav of November. 1928.

ivrLLLln H. MATTnins. 

